Tanks can be used to contain fluids under pressure. Under certain circumstances, it is desirable to have a tank with relatively thin walls and low weight. For example, in a vehicle fuel tank, relatively thin walls allow for more efficient use of available space, and relatively low weight allows for movement of the vehicle with greater energy efficiency. Recent work suggests that adsorbent materials, such as activated carbon and/or metal-organic frameworks, may be used to store gases, such as natural gas, by lowering pressures with adsorbent relative to current storage containers or increasing the storage capacity of gases in a tank. (See Zakaria et al., Int'l Journ. Rec. Rsrch. Appl. Stud. 9:225-230, 2011.)